There are just some places I have a hard time thinking of a clear description.  This is one of them, muck will have to do. Besides there are photos right here too.

Around the Lowcountry this is the preferred home of Green Herons. Dark is best, but in the sun will work for them too.

Below is one of several Green Herons that have moved into the smaller swamp by our rookery.

They fly or stalk between thickets, hiding. Every once in a while they stop by an open spot long enough for a few shots. But there seems to always be some muck involved.